HDBaseT® is a connectivity standard that enables the use of a single category cable to offer HD video, audio, Ethernet, controls, USB 2.0 and power. Transmission of data according to the HDBaseT® standard comes with several benefits that include time-sensitive transmissions, low delays and low latency. Legacy Ethernet networks are widely deployed, in both the consumer and industrial settings. Thus, it would be advantageous to utilize Ethernet networks to extend the scope of HDBaseT® networks. For example, this could extend HDBaseT® from in-room to cross-campus applications, and leverage existing pro-AV installations and interfaces to achieve end-to-end system optimization and reduced total cost of ownership.
However, HDBaseT® is based on a different protocol that basic Ethernet network equipment cannot work with. Thus, HDBaseT® data cannot be transmitted “as is” over a standard Ethernet/IP network. Therefore, there is a need to provide a way to transmit HDBaseT® data over a legacy Ethernet networks without requiring the networks to utilize non-standard equipment.
One aspect of Ethernet networks which can hinder transmission of data according to the HDBaseT® standard involves the handing of errors in packets. For example, an intermediate node in HDBaseT® networks, unlike typical Ethernet networks, forwards a packet to its destination even in the case of errors, such as Cyclic Redundancy Check (CRC) errors. In an HDBaseT® network, the fact that a packet has an error (e.g., a CRC error) does not cause the immediate discarding of the packet. In one example, the CRC error may be due to an erroneous value in the video payload (e.g., the value of a certain pixel), which may not be noticeable to a viewer who views an image whose pixels are set according to the contents of the packet. In Ethernet networks, an error in a packet, such as a CRC error, causes the discarding of the packet by an intermediate switch or by a final destination.
One scenario in which discarding of packets by an Ethernet network may become problematic is when the packets include video content, discarding the packet may lead to a black, contentless patch on a display, which may be noticeable by a human eye. More than that, such a missing packet may also cause a synchronization problem that may cause the screen to go blank and restart (in an attempt to resynchronize), which may result in not displaying content for a period that may possibly last a few seconds.
Forward Error Correction (FEC) is a mechanism often used to recover discarded or erroneous packets. Most known approaches to FEC involve utilization of a fixed size buffer receiver side and transmission overhead bandwidth used to transmit the FEC redundancy information. The current approach known in the art for FEC on an Ethernet network is described in ST 2022-5:2013—SMPTE Standard—Forward Error Correction for Transport of High Bit Rate Media Signals over IP Networks (HBRMT). This standard describes computation of packet-level parity data that enables recovery of multiple discarded packets. For example, a block of packets can be arranged in a 2D structure with parity packets being calculated for the rows and for the columns. Thus, providing FEC for L*D packets requires an additional overhead of L+D packets. This overhead can become quite significant. For example, providing FEC for 5*6=30 packets involves an overhead of at least (5+6)/(30+11)=26.8%. This overhead is often too high for many networking applications. Thus, there is a need for a way to provide more efficient FEC for transmission over communications with a low redundancy information overhead.